The Best (and Worst) Fats for Your Heart

When it comes to heart-healthy eating, nutritional advice is sometimes conflicting. One of the most confusing topics is dietary fat. What kind should you choose? How much can you eat?

Adding to the uncertainty are the U.S. government’s latest dietary guidelines, which no longer advise a limit on total fat intake. To some people, that might sound like a green light to indulge in fatty foods. Be assured, however, that’s not the case.

Here’s an overview of some of the latest findings on dietary fats—including which ones to avoid and the best choices for replacing them.

The guidelines

The 2015-2020 federal dietary guidelines made waves when they were issued, partly because they abandoned the long-recommended limits on total fat intake. Importantly, though, they did advise limits on certain types of fat—namely, saturated and trans fats.

Saturated fat is found mainly in meat and dairy products, especially full-fat dairy such as whole milk and butter. These foods also contain some natural trans fats. However, people typically eat more artificial trans fats, which are largely found in processed foods and commercial baked goods made with partially hydrogenated vegetable oil.

Of the two, saturated fat is the lesser threat: It can raise LDL (bad) cholesterol levels in the blood, but it also gives a small boost to HDL (good) levels. Trans fats, in contrast, not only increase LDL but also lower HDL.

Because of this, the dietary guidelines advise people to minimize trans fats as much as possible. They also suggest limiting saturated fat to no more than 10 percent of your daily calories. Still, the saturated fat recommendation is more lenient than the one from two major heart groups—the American College of Cardiology (ACC) and the American Heart Association (AHA)— which have long advised a cap of 5 to 6 percent.

What’s more, some widely publicized research has raised the question of whether saturated fat is truly a villain: Even though it raises LDL levels, saturated fat is not clearly tied to an increased heart disease risk, those studies suggest.

So is saturated fat not so bad after all?

Making the change

Once people trim red meat and butter from their diets, the inclination is to load up on reduced-fat processed carbohydrates, such as chips, pretzels, crackers, and bagels. That’s a misstep for several reasons. For one, refined carbs often have a large amount of added sugar and may lack fiber, vitamins, and minerals. They can also boost triglyceride levels while lowering HDL.

Instead, replace butter and bacon with nutritious and satisfying foods, such as:

• Polyunsaturated fats. Vegetable oils are a common source, but so are whole foods like fatty fish (salmon, mackerel, trout), tofu, nuts, and seeds such as sunflower and flax seeds.

• Monounsaturated fats. Certain oils, including olive, canola, and sesame, are rich in this type of fat—as are foods such as avocados, peanut butter, and many nuts and seeds.

A study of over 127,000 U.S. health professionals underscores the power of such dietary changes. Published in the Journal of the American College of Cardiology, the study estimated the effects of replacing 5 percent of a person’s calories from saturated fat with calories from other nutrients.

It found that when polyunsaturated fats were the substitute, people’s risk of developing heart disease over 30 years fell by one-quarter. Similarly, monounsaturated fat curbed the risk by 15 percent, while carbohydrates from whole grains trimmed the odds by 9 percent.

But low intake of polyunsaturated fat was blamed for an even greater share of deaths, estimated at around 10 percent, indicating that more than 1 million heart disease–related deaths each year worldwide could be avoided if people replaced saturated fat with unsaturated fats, according to the AHA.

A holistic approach

The message here is that it’s never wise to focus on limiting or increasing a single nutrient to improve your health. It is your overall diet—as part of a generally healthy lifestyle—that matters.

There is ample evidence that the Mediterranean and DASH diets are heart-healthy, for example. And they share some familiar-sounding characteristics: an emphasis on fruits, vegetables, whole grains, fish, and unsaturated fat; limits on added sugar and sources of saturated fat like butter and red and processed meats.

By keeping in mind that broader view of your overall diet quality, you’ll know that you’re on the right track.